Since it first premiered at Telluride in 2012, Joshua Oppenheimer’s The Act Of Killing has to come to be regarded as one of the seminal documentaries of the ongoing nonfiction renaissance—a disturbing look at the purge killings that swept Indonesia during the mid-’60s, as explained by the perpetrators, who’ve lived free for decades, often hailed as local political heroes.

Oppenheimer’s hotly anticipated follow-up, The Look Of Silence, opened in theaters last week. Like The Act...